Chronic myelocytic leukemia (CML): failure to detect residual normal committed stem cells in vitro

Granulocytic colonies grown in culture from marrow and peripheral blood from five patients with Ph¹-positive CML and heterozygous at the G-6-PD locus were analyzed for G-6-PD in order to identify CFU-C that do not arise from the CML clone. The patients had both B and A enzymes in normal tissues, but their CML clones typed as B. Whereas about 50% of colonies from normal subjects heterozygous as the G-6-PD locus show type-A G-6-PD and 50% type B, only two of the 1308 colonies from the CML patients had type-A G-6-PD. These data provide little evidence for persistence of normal committed stem cells in CML, a finding in contrast to that made previously in polycythemia vera, another clonal stem cell myeloproliferative disorder.